Tech Scientists Make Big Impression At Astronomy Conference

SOCORRO, N.M. July 26, 2010 – Scientists from the Magdalena Ridge Observatory – including several students – made a big splash at the biennial SPIE Conference in San Diego in late June.

Ten people presented 18 papers and posters that demonstrated to the astronomy and optics community the significant progress that is being made at New Mexico Tech’s blossoming interferometer.

Some of the brains behind the Magdalena Ridge Observatory: Ifan Payne, (from left) Chris Haniff, Van Romero and Allen Farris at the SPIE Conference in San Diego in late June.

“Four years ago [at the 2006 SPIE Conference], people might have been thinking, ‘When are they going to get something going?’,” MRO Program Director Dr. Ifan Payne said. “Two years ago, they said, ‘Well, at least they’ve started.’ This year, the sense was ‘Where the heck did the MRO come from? You’ve developed so quickly.’ It’s quite apparent that we are progressing.”

Other MRO interferometer veterans echoed those sentiments – that the astronomy community’s previous skepticism about the project has turned to interest and anticipation.

“We made a strong demonstration that we’re here to stay,” said Dr. Colby Jurgenson, interferometer Instrument Scientist. “People have begun to take us seriously.”

Fernando Santoro, lead optical mechanical engineer, said SPIE conferences give scientists the opportunity to interact with colleagues. Santoro has been working at the MRO for three years and worked for eight years at observatories in Brazil and in Tucson, Ariz.

“I have many friends at the other observatories,” he said. “SPIE is the perfect place to make contacts, talk about design and get together with colleagues who do the same thing.”

Fernando Santoro (left) and Colby Jurgenson toast a successful day of at the biannual SPIE Conference.

Instrument Technician Alisa Shtromberg, who is a master’s student in physics, made an important contact at the conference. After her talk, she met the engineer whose earlier work had provided inspiration for her research and engineering.

“I was extremely nervous and I didn’t get much feedback,” she said. “But I gained experience in giving a talk and it was neat to talk with the scientist who I’m basing my work on. It made me feel good that he confirmed that I’m headed in the right direction.”
Operations

Tech Vice President of Research Dr. Van Romero presented a talk on the operational philosophy of the MRO Interferometer.

“We aren’t a user facility,” Romero said. “No agency is providing funding so others can observe. We have to develop partnerships to go find funding for observing time.”

Most observatories have external funding sources to pay for operations. Interested astronomers and scientists then apply for time with minimal regard for funding. At the MRO, those interested in using the facility will have to come with funding – either from their home institution or from a federal agency interested in funding the research.

Overview

Eric Bakker and Michelle Creech-Eakman show off an early model of the MROI telescope mount.

MROI Project Scientist Dr. Michelle Creech-Eakman presented an invited talk on the opening day and a poster about image simulation later in the conference.

“We’ve made a lot of progress in the last two years,” Creech-Eakman said. “All of our systems are in final design review. It was good to have the team able to present so many papers and posters.”

Her opening day presentation was an overview of the Magdalena Ridge Observatory Interferometer project. She compared her presentation to a table of contents of the project and of the other talks presented by MRO staff scientists throughout the week.

“It’s important to let the community know where we stand,” she said. “As Project Scientist, I get to announce the big milestones and kind of steal other people’s thunder.”

Commissioning

MROI Unit Telescope Systems Manager Dr. Eric Bakker presented a talk about commissioning the telescope, which included an overview of each of the major subsystems.

Tech’s partners at the University of Cambridge are building the fast-tip-tilt (adaptive optics) for the telescopes. An Albuquerque company, Optical Surface Technologies is figuring the mirrors and applying the optical coatings. A Belgian company, Advanced Mechanical and Optical Systems, or AMOS, is building the telescope mounts. The first mount has been completed and will be delivered in 2011. The second and third telescopes have been ordered.

An Italian company, European Industrial Engineering, has designed the telescope enclosures and the MROI management is now soliciting bids to construct the enclosures A Tucson company, M3 Engineering, is designing the array infrastructure and foundations on which the telescopes will sit.

“I discussed all these systems and our plan for demonstrating how it will work,” Bakker said. “I focused on our activities on top of the mountain.”

Enclosures

A drawing of the custom enclosure for the MROI telescopes. The design is completed and bids are being solicited for construction of the first enclosure.

Payne’s presentation focused on the “Innovative Enclosure Design for the MROI Array Telescopes.” His talk was one of three that discussed the enclosures, with the other two were presented by Andrea Busetta and Gianpetro Marchiori of EIE, the firm that has designed the enclosures.

“The enclosures have very complicated mechanical engineering,” Payne said. “There was a lot of interest and we made a big impression.”

The enclosures must meet tight specifications. They must be able to enclose the telescope mount and still be able to sit just 23 feet apart – from center to center. In a tight configuration, there will be less than 10 inches between the shutter arms, Payne said.

“This requirement leads to an exceptionally compact and efficient design,” he said.

The domes on top of the enclosures also have to be as low as possible so the the neighboring dome does not impinge upon the field of regard form the adjacent telescope. The third important specification is weight – because the enclosures – complete with the telescopes inside – must be able to be picked up and moved.

The design includes steel struts, aluminum sandwich panel walls, a fiberglass dome and carbon fiber shutters.
In addition, the domes have a myriad of utilities: five electrical cabinets, data cables, compressed air, two cooling loops and pipes to transport the light input from the telescopes to the beam combiner.

Beam Combiner

Jurgenson presented a poster about finding first fringes using lasers in the beam combiner. Even though the interferometer has not taken delivery of its first telescope, he has shown that the facility can successfully combine separate beams to create fringes.

“Not only did we demonstrate good quality fringes with high contrast, we also combined the design with a unique approach to alignment.”

By restricting the internal freedoms within the beam combiner, the system will have a higher degree of stability, he said.
Romero said, “Colby was the belle of the ball. He has successfully gotten fringes, which is significant. Everybody wanted to talk to him. People are very interested in what he’s doing.”

Optics

Jurgenson also presented a talk about the novel optical coatings that will be used in the Beam Combiner. Jurgenson and doctoral student Kristina Nyland have done significant research into finding the best optical coatings for the beam combiner optics in the beam combining facility .

There are three optimized coatings with multiple material layers; each coating has a different function. One coating minimizes reflection, while the other two optimize splitting and recombining the light beams.

The combiner substrates are fused quartz – or Infrasil – which have been manufactured by IC Optical Systems in the UK. The optical coatings have been applied in Albuquerque at Optical Surface Technologies, a company partially owned by New Mexico Tech.

Fringe Modulator

Doctoral student Tyler McCracken presented his research and development for the new modulator, which is the device that will correct for atmospheric distortions of the optical wavefronts.

Doctoral student Tyler McCracken uses a snack-on-a-stick as a pointer to explain his poster about the modulator he is developing for the MROI.

The modulator includes hardware and software that will gauge the distortion – or twinkle – from the atmosphere and adjust the fringe tracker (or beam combiner). The device introduces an optical path difference. The device synthesizes or models the fringes and tells the delay lines about any path corrections that need to be applied.

“You’re talking about moving a mirror one micron,” McCracken said. “So you need to know that accurately. The delay lines correct for these small aberrations – or wiggles – in the light. The modulator allows us to get the measures we need.”

The device will include an off-the-shelf electric modulator, gold-plated mirrors, embedded system controls, a field programmable gate array, a high-voltage digital-to-analog card, string gauges, resistors and an analog-to-digital converter.

McCracken is also employing a new technique developed at Cambridge to optimize the waveform, which gives a stable pattern over time.

“Instead of sampling fast and constantly correcting, if you get an optimized waveform, you can extend it to minutes, hours or even an entire observing night,” he said. “It’s all about computing power and what you require from your hardware and software.”

Alignment System

Alisa Shtromberg, a master’s student in physics, gave a talk on the alignment system she is designing with Jurgenson.

“We’re automating the alignment system, which hasn’t been done before,” she said. “From the telescopes to the delay lines to the beam combiner – we’re aligning all three systems and automating it.”

Each of those three systems will have an internal alignment system, but the three separate systems also need to be aligned with each other, she said.

Alisa Shtromberg and Van Romero discuss the finer points of interferometry at the 2010 SPIE Conference.

Shtromberg is employing complex algorithms and computer programming to design a system that will function with minimal human input.

“Even using algorithms, it’s still an iterative process,” she said. “It will take time to make it perfect, but we’re trying to take out the human error.”

The alignment system will be installed between the delay lines and the beam combiner. The device, nicknamed the Magic Optical Box, or M.O.B., is in the fabrication in Albuquerque. The M.O.B. will shoot light in two directions, detect misalignments and then calibrate the systems.

“One of the biggest issues in an interferometer is losing time during aligning or losing quality of fringes due to misalignment,” Shtromberg said.

The device must be able to align the system within one hour every night as part of the pre-start-up process.

“This is a huge task,” she said. “It’s conceptually simple, but the devil is in the details.”

Custom Software

Allen Farris, senior software engineer for the interferometer, presented a talk about the computer infrastructure that is being developed for the facility.

“We’re developing our own framework for interfacing protocols in a code-generating process,” he said. “A lot of the software for the individual systems is being designed and developed by third parties. Our supervisory software forms the glue that pulls it all together in a unified system.”

He said low-level systems will govern the mirrors, motors and other systems. His custom software will manage the entire system.
A common approach to designing software infrastructure for astronomical systems has been based on the Common Object Request Broker Architecture, or CORBA.

“The disadvantage of the CORBA-based approach is that it’s a heavyweight software and imposes a heavy footprint,” Farris said. “So, we chose not to use that. We’re trying to keep our dependency on other software to a minimum so we can manage the life of our software systems.”

Farris is also developing an innovative code-generation software that will oversee the configuration of the system.

“We have a way of describing each interface to a system – like the mount or the alignment system or the fringe tracker,” he said. “We can describe what the system does, export that data to a spreadsheet and then the code generator creates an interface module.”

Once the interferometer becomes operational with multiple telescopes and is producing science and generating engineering data, the supervisory software will identify and memorize those configurations in an integrated database.

Farris is also building an advanced graphic-user interface that will allow an astronomer to operate the mountaintop system in real-time – largely from the Operations Center in Socorro.

“This software system will make it all work together,” he said.

The Mechanics

An artist's rendering of the Magdalena Ridge Observatory Interferometer in the 'closed pack array.' Staff scientists from the facility presented a series of posters and papers at the SPIE Conference in San Diego in June.

The MROI Beam Combining Facility.

Santoro presented a poster that explained the mechanical systems involved in the interferometer.

“This was the first time we showed all the hardware together from the telescopes to the fringe tracker,” he said. “Other interferometers have so many more reflections that they don’t allow for viewing of faint objects. We have a very low number of reflections and that is the main engineering challenge.”

The MROI optical train includes just 19 reflections, compared to the Very Large Telescope Interferometer (VLTI, where Santoro formerly worked), which has more than 40 reflections. With each reflection, a percentage of photons is lost to deflection or dispersal.

Santoro said the entire mechanical system has also been designed to maximize stability. That means he has limited the number of adjustments that can be made – sacrificing a bit of freedom for the sake of improving the integrity of the mechanical framework.

Next Time

The MRO Interferometer staff already is anticipating another successful showing at the 2012 SPIE Conference in the Netherlands.

“We are confident that we’ll be showing real hardware on the ridge in two years from now,” Santoro said. “That’s our goal for the next meeting – show good design that is right on specifications.”

Creech-Eakman said she anticipates having at least two telescopes on the ridge within two years. “Hopefully we’ll be nearing first fringes in 2012 when we speak in the Netherlands,” she said.